guix-package: Add '--search'.

* guix-package.in (find-packages-by-description): New procedure.
  (show-help, %options): Add '--search'.
  (guix-package)[process-query]: Add support for '--search'.
* doc/guix.texi (Invoking guix-package): Document it.
* tests/guix-package.sh: Add tests.

doc/guix.texi

@@ -23,6 +23,7 @@
 @title{GNU Guix Reference Manual}
 @subtitle{Using the GNU Guix Functional Package Manager}
 @author Ludovic Courtès
+@author Nikita Karetnikov
 
 @page
 @vskip 0pt plus 1filll
@@ -542,6 +543,14 @@ availability of packages:
 
 @table @option
 
+@item --search=@var{regexp}
+@itemx -s @var{regexp}
+List the available packages whose synopsis or description matches
+@var{regexp}.
+
+For each package, print the following items, separated by tabs: its
+name, version, and the source location of its definition.
+
 @item --list-installed[=@var{regexp}]
 @itemx -I [@var{regexp}]
 List currently installed packages in the specified profile.  When

guix-package.in

@@ -235,6 +235,31 @@ both when LINK already exists and when it does not."
              (switch-link)))
           (else (switch-link)))))                 ; anything else
 
+(define (find-packages-by-description rx)
+  "Search in SYNOPSIS and DESCRIPTION using RX.  Return a list of
+matching packages."
+  (define (same-location? p1 p2)
+    ;; Compare locations of two packages.
+    (equal? (package-location p1) (package-location p2)))
+
+  (delete-duplicates
+   (sort
+    (fold-packages (lambda (package result)
+                     (define matches?
+                       (cut regexp-exec rx <>))
+
+                     (if (or (and=> (package-synopsis package)
+                                    (compose matches? gettext))
+                             (and=> (package-description package)
+                                    (compose matches? gettext)))
+                         (cons package result)
+                         result))
+                   '())
+    (lambda (p1 p2)
+      (string<? (package-name p1)
+                (package-name p2))))
+   same-location?))
+
 
 ;;;
 ;;; Command-line options.
@@ -266,6 +291,8 @@ Install, remove, or upgrade PACKAGES in a single transaction.\n"))
       --verbose          produce verbose output"))
   (newline)
   (display (_ "
+  -s, --search=REGEXP    search in synopsis and description using REGEXP"))
+  (display (_ "
   -I, --list-installed[=REGEXP]
                          list installed packages matching REGEXP"))
   (display (_ "
@@ -311,6 +338,10 @@ Install, remove, or upgrade PACKAGES in a single transaction.\n"))
         (option '("verbose") #f #f
                 (lambda (opt name arg result)
                   (alist-cons 'verbose? #t result)))
+        (option '(#\s "search") #t #f
+                (lambda (opt name arg result)
+                  (cons `(query search ,(or arg ""))
+                        result)))
         (option '(#\I "list-installed") #f #t
                 (lambda (opt name arg result)
                   (cons `(query list-installed ,(or arg ""))
@@ -532,6 +563,7 @@ Install, remove, or upgrade PACKAGES in a single transaction.\n"))
                                  name (or version "?") output path))))
                      installed)
            #t))
+
         (('list-available regexp)
          (let* ((regexp    (and regexp (make-regexp regexp)))
                 (available (fold-packages
@@ -554,6 +586,16 @@ Install, remove, or upgrade PACKAGES in a single transaction.\n"))
                              (string<? (package-name p1)
                                        (package-name p2)))))
            #t))
+
+        (('search regexp)
+         (let ((regexp (and regexp (make-regexp regexp))))
+           (for-each (lambda (p)
+                       (format #t "~a\t~a\t~a~%"
+                               (package-name p)
+                               (package-version p)
+                               (location->string (package-location p))))
+                     (find-packages-by-description regexp))
+           #t))
         (_ #f))))
 
   (setlocale LC_ALL "")

tests/guix-package.sh

@@ -1,5 +1,6 @@
 # GNU Guix --- Functional package management for GNU
 # Copyright © 2012, 2013 Ludovic Courtès <ludo@gnu.org>
+# Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
 #
 # This file is part of GNU Guix.
 #
@@ -68,6 +69,10 @@ then
 
     test "`guix-package -p "$profile" -I 'g.*e' | cut -f1`" = "guile-bootstrap"
 
+    # Search.
+    test "`guix-package -s "GNU Hello" | cut -f1`" = "hello"
+    test "`guix-package -s "n0t4r341p4ck4g3"`" = ""
+
     # Remove a package.
     guix-package --bootstrap -p "$profile" -r "guile-bootstrap"
     test -L "$profile-3-link"